.absolute(@top:initial; @right:initial; @left:initial; @bottom:initial){
  position: absolute;
  top: @top;
  left: @left;
  right: @right;
  bottom: @bottom;
}
.fixed(@top:initial; @right:initial; @bottom:initial; @left:initial) {
  position: fixed;;
  top: @top;
  left: @left;
  right: @right;
  bottom: @bottom;
}
